1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for releasing a radio bearer in a wireless communication system.
2. Related Art
Wireless communication systems are widely used to provide a voice service or a packet service. A multiple access system supports multi-user communication by sharing available system resources. Examples of the multiple access system include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, etc.
3-rd generation partnership project (3GPP) release 8 introduces 3GPP long term evolution (LTE) that is an evolution of a universal mobile telecommunication system (UMTS). The 3GPP LTE uses OFDMA in a downlink, and uses single carrier-FDMA (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having 4 antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
A radio bearer is a logical path for data transmission between a user and a network. The radio bearer can be created, re-established, and released anytime at the request of the user or the network. In general, when the radio bearer is released, entire data stored in a buffer of each layer is directly discarded without performing any process on the data.
However, if the entire data is directly discarded when the radio bearer is released, it may cause ineffective use of resources. This is because, when successfully received data is discarded due to the release of the radio bearer, the data may be redundantly transmitted again thereafter.